In certain applications of downhole well pumps, solids particulates become entrained in the pumped fluid and, during periods of pump shutdown, such particulates tend to settle out of the fluid and collect at the pump including the pump discharge ports, resulting in clogging of the pump, or damage to the pump, or both.
Certain applications of rod actuated downhole well pumps require relatively intermittent pump operation and also comprise applications where particulate fines are ever present in the pumped fluid. For example, gas wells in certain types of earth formations, such as coal beds, typically require intermittent pumping to remove liquid, primarily water, from the wellbore to avoid interfering with gas flow. Since operation of the pump is often quite intermittent and long periods of inactivity occur, the long column of liquid in the well tubing string will result in substantial settling of abrasive solids particulates at the bottom of the tubing string whereupon the pump mechanism may be clogged or damaged by the collection of such material. The present invention overcomes this problem, as will be appreciated by those skilled in the art of rod actuated well pumps.